CPM - Certified Plant Mechanic Power Plant Machinery Questions and Answers

Question 1

In a steam power plant, what is the primary function of a deaerator in the boiler feedwater system?

Accepted Answer

To remove dissolved gases, primarily oxygen, from the feedwater.

Answer

To filter out suspended solids and sediment.

Answer

To increase the pressure of the feedwater before it enters the boiler.

Answer

To chemically treat the water to adjust its pH level.

Question 2

A plant mechanic observes a centrifugal pump making a loud rattling noise, similar to gravel passing through it, along with fluctuating discharge pressure and flow. Which of the following is the MOST likely cause of these symptoms?

Accepted Answer

Cavitation

Answer

Pump-motor misalignment

Answer

Worn bearings

Answer

A clogged discharge line

Question 3

Which type of steam turbine is designed to exhaust steam at a pressure below atmospheric pressure into a condenser, maximizing the energy extracted from the steam for power generation?

Accepted Answer

Condensing turbine

Answer

Back-pressure turbine

Answer

Extraction turbine

Answer

Topping turbine

Question 4

What is the principal role of an economizer in the boiler system of a power plant?

Accepted Answer

To preheat the incoming boiler feedwater using waste heat from flue gases.

Answer

To superheat the steam after it leaves the boiler drum.

Answer

To control the air-to-fuel ratio for optimal combustion.

Answer

To remove moisture from the steam before it enters the turbine.

Question 5

In large rotating machinery like turbines and generators, what is the specific function of a thrust bearing?

Accepted Answer

To absorb and manage axial forces along the length of the shaft.

Answer

To support the radial load or weight of the rotor.

Answer

To reduce the rotational speed between the turbine and generator.

Answer

To dampen torsional vibrations within the shaft.

Question 6

Which of the following inspections on a large industrial gas turbine is the most comprehensive, typically requiring the turbine casing to be removed for direct examination of hot gas path components like blades and nozzles?

Accepted Answer

Major Inspection / Hot Gas Path Inspection

Answer

Borescope Inspection

Answer

Combustion Inspection

Answer

Vibrational Analysis